Parents love its price and convenience; kids go for the creamy taste. But the beloved peanut butter sandwich is missing this year in the cafeteria at Rock Creek Elementary School and at many school lunch tables.

Snacking on the sack-lunch staple is no longer an option for the 550 children who eat at the O'Fallon, Mo., school. Rock Creek has gone peanut-free, and with it go those nutty sandwiches.

Locally, the Oak Park Unified School District is considering doing the same. On last week's school board agenda, a food allergies policy was up for approval; among the provisions, "they were looking at peanuts and tree nuts," said the district's director of child nutrition, Laurel Goins. "Obviously, peanuts is a more common allergy."

The policy went back for revisions, but Goins said the message is clear. "We want everyone to be safe," she said. "It's probably been a long time coming, so why not now?"

Schools and parents across America have grappled for years with safeguards for children with peanut allergies. From peanut-free tables in the cafeteria to omitting those products from school menus and classroom treats, districts across the nation have made a variety of arrangements to help protect those students who could suffer allergic reactions, some that could be life-threatening.

A growing number of schools across the nation are saying no to nuts completely. And some experts say it's a measure more schools will consider as the number of children in the United States with a peanut allergy continues to rise.

"It sounds goofy, but to these kids a peanut butter sandwich is like a loaded gun," said Deanne McCullough, principal at Rock Creek, where more than a dozen students have some type of allergy to peanuts. "Their lives are already impacted so much. At school, they can at least have that part of their life be normal."

During the past 10 years, the incidence of food allergies has doubled, according to the Food Allergy & Anaphylaxis Network, an advocacy group based in Fairfax, Va.

One study conducted in 1997 and repeated in 2002 showed that peanut allergies had doubled in children during that five-year span, the group says.

Scientists are still trying to figure out why. One of many theories is that a child's immune system misidentifies certain food as harmful because children are exposed to fewer germs these days. Another is simply that peanut allergies are being recognized more. In 2006, the group estimated 435,000, or less than 1 percent, of school-age children had a peanut allergy.

The number of districts nationwide that have some type of peanut ban is increasing, according to a survey the School Nutrition Association conducted this spring. Of 1,200 districts nationwide that responded, 18 percent banned peanuts because of food allergies. That's up from 12.7 percent in 2005, the last time the association surveyed districts.

After learning that two students at Rock Creek Elementary could have life-threatening reactions to airborne allergens from peanuts, the school followed the advice of a pediatrician and banned peanuts, peanut products and items containing peanuts this year, McCullough said.

In a letter to parents last month before school started, McCullough called the ban essential. Two students at the school have such severe allergies to peanuts that eating, touching or even smelling peanuts can be harmful and in some cases, life-threatening, McCullough said.

But some parents do not agree with the ban.

The school's decision surprised Jennifer Kaiser, a Rock Creek mother who describes one of her daughters as a "peanut butter monster." But she says it's about more than having finicky eaters to feed in her family.

"It's not just about peanut butter," Kaiser said. "We are educators and parents and I think our biggest job would be to help this child become confident and secure with their allergy. This is an extreme measure that doesn't do anything to help the child in the long run. It's setting up an unrealistic environment."

Parents of the most severely allergic children at Rock Creek declined to comment.

Stephanie Clawson, a St. Charles County, Mo., mother, understands their plight. At 15 months old, her daughter Isabelle touched the peanut butter sandwich her mom was eating and broke out in hives on her chest. After a visit to the doctor, Clawson learned that the smallest amount of peanut butter could threaten her daughter's life.

Isabelle's kindergarten year at J.L. Mudd Elementary made her mom nervous, even though the half day of school didn't involve lunch. Isabelle's teacher had never dealt with a peanut allergy before. A note was sent home with parents to avoid sending snacks containing peanuts to class. Just in case, Isabelle had a separate box of snacks to choose from that were safe for her.

As difficult as keeping your child away from peanuts or peanut products on a daily basis can be, getting other parents to grasp the extent of the issue is another problem, Clawson said.

"If it was a matter of hives or getting itchy, I could understand them not wanting to change their child's whole menu. But this is more serious than that," Clawson said. "I have very picky children, too, and they will not starve."

— Star staff contributed to this report.